Does the glucose drink have calories? The Facts Behind Your Medical Test

November 5, 2025 •

4 min read

A 75-gram oral glucose tolerance test (OGTT) drink, commonly used for medical screening, contains approximately 300 calories. The question, does the glucose drink have calories, is a critical one for patients monitoring their dietary intake, but understanding the medical necessity behind this caloric load is key.

Quick Summary

The glucose drink used for medical testing contains a specific, controlled amount of calories derived from pure glucose. This sugar load is required to accurately test the body's metabolic response, serving as a diagnostic tool for diabetes and gestational diabetes.

Key Points

Yes, the drink contains calories: The glucose drink contains a specific amount of calories, as it is a pure carbohydrate solution.
Calories vary by dosage: A standard test drink can contain 200 (50g), 300 (75g), or 400 (100g) calories, depending on the test requirements.
The calories are for medical testing: The controlled caloric load is medically necessary to measure how your body processes sugar, not for nutrition.
Follow fasting instructions strictly: For an accurate Oral Glucose Tolerance Test (OGTT), you must fast for 8-12 hours beforehand.
Standard vs. alternative options: Both standard (Glucola) and natural alternative drinks are equally effective, but may differ in taste and ingredients.
Be prepared for the test: Bring entertainment for the waiting period and have a snack ready for after the final blood draw.

Understanding the Caloric Content of Glucose Drinks

The short answer to "Does the glucose drink have calories?" is a resounding yes. The glucose solutions administered during medical tests, such as the Oral Glucose Tolerance Test (OGTT), are specifically designed to deliver a precise dose of pure glucose, which is a carbohydrate. As with all carbohydrates, glucose contains calories, providing energy to the body's cells. For medical purposes, this controlled caloric intake is essential for evaluating how your body processes sugar.

The Calorie Count by Glucose Load

The total number of calories in a glucose drink depends directly on the amount of glucose it contains. Different tests require different dosages, with the most common being 50, 75, or 100 grams of glucose. Since every gram of carbohydrate contains roughly 4 calories, the calculations are straightforward.

Typical Calorie Breakdown:

50-gram dose: Contains approximately 200 calories. This is often used for the initial glucose challenge test, especially during pregnancy.
75-gram dose: Contains approximately 300 calories. This is the standard dose for diagnosing type 2 diabetes and gestational diabetes.
100-gram dose: Contains approximately 400 calories. This higher dose is sometimes used for a more detailed assessment, particularly in cases of gestational diabetes following an irregular screening.

These calories are not negligible, which is why patients should be aware of them, particularly if they are monitoring their daily intake for weight management or other health reasons. However, a medical test is a necessary exception, and these calories serve a specific diagnostic purpose rather than a nutritional one.

Comparing Different Glucose Drink Formulations

While the goal of all glucose tolerance test drinks is the same—to provide a standardized glucose load—the specific formulations can vary. Historically, most test drinks were standard, artificially flavored and colored sugar solutions. However, alternatives have emerged to address taste and ingredient concerns.


Feature	Standard Glucola	Natural Alternatives (e.g., Fresh Test)
Ingredients	Water, dextrose (from corn), citric acid, artificial flavorings, preservatives, and sometimes artificial colors.	Water, dextrose (from corn), citric acid, and natural flavorings. Often free of dyes and preservatives.
Tolerance	Many find the taste unpleasantly sweet and syrupy, which can lead to nausea.	Reported to be easier to consume and gentler on the stomach for many patients.
Effectiveness	Medically proven and universally accepted for diagnostic accuracy.	Considered equally effective at delivering the required glucose load for accurate screening.
Availability	More widely accessible through most medical clinics and laboratories.	Still gaining traction, but becoming a more requested option for those seeking a cleaner ingredient profile.

The Role of the Glucose Drink in Medical Testing

The calories in the glucose drink are not just empty energy; they are the central component of the test itself. An Oral Glucose Tolerance Test (OGTT) measures how effectively your body processes sugar over a period of time.

How an OGTT Works

During an OGTT, the controlled intake of a high-glucose solution allows medical professionals to observe the body's metabolic response.

Baseline Measurement: A blood sample is taken after a period of fasting to establish your initial blood glucose level.
Glucose Load: You consume the entire sugary drink quickly.
Timed Blood Draws: Subsequent blood samples are taken at specific intervals (typically 1 and 2 hours after the drink) to measure how your blood sugar levels rise and fall.

By tracking these changes, doctors can identify potential issues with insulin production or utilization, which can signal pre-diabetes or diabetes. Without the precise and rapid sugar spike caused by the drink's caloric content, the test would be ineffective.

Preparation and Aftercare for a Glucose Test

For the most accurate test results, proper preparation is key. This is a medical procedure, and you should follow your doctor's instructions carefully.

Preparing for Your Glucose Test

Maintain a normal diet: In the days leading up to the test, it is important to continue your usual diet without significant changes, unless otherwise instructed. Severely restricting carbohydrates could affect your results.
Fasting: For the main OGTT, you will need to fast for 8-12 hours beforehand. This means no food or drinks (except water).
Medication and Activity: Discuss all medications with your doctor, as some can impact results. Avoid strenuous exercise on the day of the test.

Managing Your Diet After the Test

Once the test is complete, your fasting period ends, and you can resume normal eating. It is important to have a snack or meal ready, as the high sugar load followed by fasting can cause some people to feel lightheaded. While the calories from the test are accounted for during the procedure, you should return to your regular, healthy eating patterns immediately to avoid any prolonged impact on your blood sugar levels.

Conclusion: The Necessary Calories

In conclusion, the answer to does the glucose drink have calories is undeniably yes, and for a critical reason. The calories in the standardized glucose solution are not incidental but are a fundamental part of a diagnostic tool used to measure your body's ability to process sugar. While the sudden intake of sugar and its associated calories may feel unusual or unpleasant, it is a necessary procedure for screening for conditions like diabetes and gestational diabetes. Understanding the purpose of these calories can help you feel more informed and prepared for the test.

To learn more about the specifics of the test and its implications, consult resources from authoritative health organizations.

Glucose Tolerance Test - MedlinePlus

Frequently Asked Questions

The drink is made with a high concentration of glucose to create a controlled and rapid spike in blood sugar. This allows doctors to accurately measure how your body responds and processes the sugar over a specific period, which is the entire purpose of the test.

During pregnancy, the glucose test is used to screen for and diagnose gestational diabetes, a form of diabetes that can develop during pregnancy. Detecting and managing this condition is important for the health of both the mother and the baby.

Yes, some natural alternatives like the Fresh Test exist, which contain natural flavorings and no artificial dyes. They are considered equally effective as long as they deliver the exact required glucose load. You should discuss this option with your healthcare provider.

Feeling nauseous or dizzy is a common side effect for some people. If you feel unwell, it is important to inform the medical staff, who may have you lie down. Serious side effects are rare.

For the one-hour glucose challenge test, especially during pregnancy, fasting is not always required. However, for the more extensive two or three-hour glucose tolerance tests, an 8-12 hour fast is necessary.

No, you must drink the standardized glucose solution provided by the lab. Using a different drink would compromise the test's accuracy, as the medical staff needs to know the exact amount and type of sugar you are consuming.

If you eat or drink anything other than water during the testing period, it can affect your blood sugar levels and lead to an inaccurate result. In most cases, you would have to retake the entire test.